L: Limited applicability or conditional based on configuration (see notes)

Notes & Guidance

Track confidence and accuracy: Select a model with magnetometer (-GEO or -3D) if a high confidence and best accuracy of the position tracks is important. For SeaTag-LOT, position tracks are based on light and SST observations; original data sources in many cases of lesser quality or more noisy than geomagnetic measurements. The advanced ‘biased random walk’ processing for SeaTag-LOT implemented in Track&Loc will weigh all available factors including animal dispersion capabilities to provide a most probable track connecting the known start and pop-up positions. Through the use of these constraints however, the method may also obscure substantial track errors that are not necessarily fully reflected in the tracks confidence interval [5]. The accuracy for both methods will be location specific, reflecting the steepness and modeling error of the SST and magnetic field intensity gradient in a given area. Based on an evaluation of global SST and magnetic field intensity gradients between 45° N and 45° S, and identified gradient modeling and measurement error sources, error modeling predicts a mean latitude error of 39 nautical miles for the geomagnetic method. For the light and SST based method, the mean error prediction is 91 to 303 nautical miles under best and reasonable worst case SST model error and measurement assumptions respectively [5]. This is at the point of their full manifestation because the biased random walk constraints of Track&Loc will act to limit track errors resulting from fleeting or temporary model or measurement errors. Longitude accuracy and confidence will be similar for any S.A.M. model (on the order of 0.5° longitude / 30 nautical miles) because longitude is always based on light observations and all S.A.M. tags use the same light observation approach and sensing elements to determine local apparent noon.

Vertical habit studies: Only SeaTag-3D includes a depth sensor. Use this tag either exclusively or in a mix with the other S.A.M. models for tagging incorporating vertical habitat studies. Maximum diving depth of -LOT and -GEO tagged animals can be inferred in some cases from the minimum daily temperature reported by these tags as interpreted in the context of depth & temperature histograms returned by -3D.

Extended operation in darkness: Specify S.A.M. tags with a small internal battery augmenting the stored solar power for studies of animals that may not experience significant daylight each day. A battery is not available for -LOT, is an option for -GEO and is standard for -3D. Without a battery, S.A.M. tags will sustain geo-positioning observations for about three days in darkness, and maintain the clock for another three days thereafter. Tags experiencing power loss will fire their release upon returning to sunlight (tag shed by a life or decomposing animal), report the power loss status and transmit collected archival data.

High resolution time series data: Specify SeaTag-3D when time series sensor data is needed. Data is transmitted as sensor scan messages. Each time stamped message contains the momentary values of all sensors. Sampling rate is selectable at a fastest of 16 seconds, and memory capacity is sufficient to hold 78 days worth of sensor scans at that rate, or 3.2 years at the commonly used 4 minute interval. Sensor scan messages can be prioritized for preferred Argos transmission if depth readings are beyond a specified threshold (deep dive profile transmission) or for the first specified number of days after tagging (post-release recovery or mortality monitoring). Full dataset recovery is possible through physical recovery of the tag, supported by its long transmission endurance and resulting opportunity for radio homing or recovery upon beaching.

Optimization for mortality studies: SeaTag-LOT is capability and cost optimized for mortality studies in pelagic species that commonly visit the proximity of the surface and exhibit vertical dive behavior that subjects them to temperature gradients. Target species include tuna and billfish. The tag determines mortality through a drop in the maximum observed daily temperature gradient. Observations have shown that tags on life bluefin tuna generally experience temperature changes of at least 2 °C / minute while floating tags or tags on the bottom tend to exhibit less than 0.2 °C / minute when sampled at four minute intervals.

Smallest size and lowest drag: SeaTag-LOT and SeaTag-GEO are best suited for tagging small animals due to their smallest size and lowest drag.